Europeans are notoriously squeamish about genetically modified (GM) crops. In America, however, they reign supreme. Since farmers first planted GM soya in 1996, engineered crops have steadily conquered America’s vast farmland. Last year 93% of cotton and soya acres contained genetically engineered crops, as did 86% of corn acres. In the past the Agriculture Department (USDA) has placed relatively meagre limits on this expansion. This month, however, that may change.

Alfalfa, that humble feedstuff, is at the heart of an intense debate. The USDA will soon decide how to regulate Roundup Ready alfalfa, engineered by Monsanto to resist a chemical used to kill weeds.